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Biomedical subjects

G Petkov

Publications and source records attributed to G Petkov.

At least 19 recordsLinked to original sources
PubMed2004

Safety investigation of team performance in accidents.

The paper presents the capacities of the performance evaluation of teamwork (PET) method. Its practicability and efficiency are illustrated by retrospective human reliability analyse of the famous nuclear and maritime accidents. A quantitative assessment of operators' performance on the base of thermo-hydraulic (T/H) calculations and full-scope simulator data for set of NPP design basic accidents with WWER is demonstrated. The last data are obtained on the 'WWER-1000' full-scope simulator of Kozloduy NPP during the regular practical training of the operators' teams. An outlook on the "evaluation system of main control room (MCR) operators' reliability" project, based on simulator data of operators' training is given.

Disaster Planning↗
PubMed1990

Two novel polyadenylation mutations leading to beta(+)-thalassemia.

In an ongoing effort to identify point mutations causing beta-thalassaemia, we have found two previously unreported mutations which are located in the Poly A site of the beta-globin gene. The screening programme used amplified DNA and dot-blot hybridization with several 32P-labelled oligonucleotide probes. DNA samples which remained unidentified by this methodology were subjected to sequencing with 32P-labelled primers and modified T7 DNA polymerase. The newly discovered mutations were confirmed by the dot-blot hybridization technique. One type concerned an AATAAA----AATGAA mutation in the polyadenylation site and was found in one family from Yugoslavia (including one patient with the C----T mutation at codon 29 in trans), one from Bulgaria (the patient had the G----A mutation at IVS-I-110 in trans), and one from Greece (this patient had the C----G mutation at IVS-II-745 in trans). Haematological data for three simple heterozygotes suggested a rather mild beta(+)-thalassemia. The second type involved an AATAAA----AATAGA mutation and was found in one family from Malaysia. The propositus had the beta E mutation on the other chromosome, was originally diagnosed as mild Hb E-beta(+)-thalassaemia, and had Hb A and Hb E percentages which were nearly the same.

Adult↗
PubMed1987

[Microbial contamination of the air in the commercial production of poultry meat].

Microbiologic studies were carried out on industrial premises for the raising of broiler birds on deep litter over a flooring area of 2000 m2 at mechanical ventilation of negative pressure. The microbial count was established through culturing in meat-and-peptone agar regarding the presence of coli bacteria, microscopic fungi, hemolytic cocci and Salmonellae in the air. Studies were also performed to establish the contamination of the atmospheric air at a distance of 10 m surrounding the premises, of the litter as well as of the feed and the soil in immediate proximity to the buildings. It was found that as a result of raising the 'biologic loading' of the ecotope by 60 per cent the microbial contamination of the air in the industrial buildings rose. The basic sources of contamination were the deep litter, the atmospheric air introduced by the ventilation system, the soil, and the feed.

Air Microbiology↗
PubMed1987

[Possibilities for decontaminating the air in commercial poultry breeding].

Experiments were carried out in bacteriologic and fumigation chambers to restrict the microbial contamination of the air on industrial premises via artificial ionization of the air or aerosol spraying of water and disinfectants. It was shown that the differential application of artificial ionization of air was appropriate in that the demands of the technology aiming at maximum stimulation of productivity were met as suggested by the authors. Besides, this technology provided for the treatment of air of high concentration of air ions coming in the outer space at the rate of 150-200 thou per cu. cm3 from production premises. It is expedient to practise the aerosol dispersion of water in the production buildings for the cell raising of birds as an opportunity for limiting the microbial contamination of air and the lowering of the unfavourable effect of high summer temperatures. It was found that in this country's conditions of industrial poultry raising most rational was the use of lactic acid at the rate of 0.004 per cu. m air, used as a 0.002 percent solution.

Aerosols↗
PubMed1986

[Microbial contamination of the air in the housing of laying hens].

Studied were buildings of one and the same design, sizing 92/12/3.5 m. Building A of mechanical ventilation through negative pressure housed 9,000 layers of the White Leghorn breed, and building B of ventilation with equated pressure, providing the same debit per kg biomass, housed 20,000 layers. The air in the buildings, in the close surrounding as well as the feed and soil were investigated with regard to the total counts of organisms as cultured in meat and peptone agar and with regard to the individual counts of coli bacteria, microscopic fungi and hemolytic cocci, and Salmonellae. It was found that the microbial contamination of air on the productional premises and of atmospheric air closely surrounding the buildings, was higher in building A. There were differences in the microflora of the air at the level of the individual stories in building B. The differences in the microbial contamination of air between the two buildings was the result of reconstructions concerning the ventilation system as well as of making it more effective.

Air Microbiology↗
PubMed1985

Haplotypes and levels of fetal hemoglobin and G gamma to A gamma ratios in Mediterranean patients with thalassemia minor and major.

This study concerned the gamma chain composition of Hb F and the haplotypes of 44 patients with beta-thalassemia major or intermedia and many of their relatives. Seventeen patients came from Northern (Turkish) Cyprus, 12 from the Istanbul area, and 15 from Macedonia and Bulgaria. Analysis of the A gamma T-G gamma-A gamma I ratio was made by HPLC, while haplotyping involved seven restriction sites. Specific haplotypes were present in certain populations; haplotype I [1] is the dominant type among North Cypriot thalassemia patients. Numerous types were seen in the patients from the Balkan countries. A direct relationship between the A gamma to G gamma ratios and the haplotypes, which exists among black beta-thalassemia heterozygotes [3], was also observed among these Mediterranean patients, although such analyses were considerably complicated by extensive blood transfusion therapy. Haplotypes without the Hinc II restriction site within the psi beta gene were associated with lower G gamma values than those that had this polymorphic site. The A gamma T chain was observed in a small number of beta-thalassemia homozygotes and heterozygotes. Three thalassemia chromosomes with slightly different haplotypes and one normal chromosome with a related haplotype were associated with the gamma 75 Ile----Thr substitution. A few patients with a thalassemia intermedia were heterozygotes for beta-thalassemia with either haplotypes V or VII [1] while the "nonthalassemic" chromosome had a haplotype I, which is the most common "beta-thalassemic" haplotype among the Mediterranean population(s). Detailed analyses of this chromosome have not been completed.

Adolescent↗
PubMed1984

[Microbial content of the air in poultry houses].

The industrial animal-breeding complex is characterized as an ecotechnical system the function of which is determined by the action of antropogenic factors. It has been demonstrated that up to now the stress of antropogenic activity has been laid on the optimization of the abiotic factors. The control and optimization of the biotic factors has constituted a problem for industrial poultry breeding, especially important being the microbial content of air. Investigations have shown that with the industrial raising of birds air microbism has assumed the importance of a factor that lowers the effectiveness of the technologies applied. The factors have been discovered that govern the extent of microbial contamination of air. Results of experiments in productional poultry houses and climatic chambers have led to the offer of measures aimed at limiting the microbial contamination of air in the industrial raising of birds.

Air Ionization↗
PubMed1984

[Poultry meat production with varying densities in raising the broilers].

Tests were carried out at two densities of raising the broilers on productional premises--16.6 and 23.6 per 1 m2 of flooring. Both the prophylactic programme and the conditions of tending and feeding were one and the same on the premises used. Each one of these was supplied with a cell in which birds were kept at the same density value as that on the other premise. Thus, four groups were formed in all: I--broilers kept at the rate of 16.6 per sq. m, II--broilers raised on the premise at 23.6/m2, III--broilers kept in a cell at 16.6 on the same premise where the other birds were kept at 23.6, and IV--broilers kept at 23.6 per sq. m. on the premise where the rate concerning the other birds was 16.6. The basic integral indices of the production effectiveness as well as the bioconversion of the dietary amino acids were followed up. It was found that during the transitional period the lower productional results with the broilers raised at higher densities were due to the action of biotic factors, and, more specifically, to the changes in the homotypical reactions that were the result of the higher density of raising. In the summer season the pesimal effect produced was a complex one, including not only the biotic factors but also the unfavourable action of the temperature and humidity regime.

Amino Acids↗
PubMed1984

[Evaluation of abiotic ecological factors and their dynamics at various densities in raising broilers].

Three productional experiments were carried out in which the broilers were kept on unified premises under one and the same technology, but at various densities of raising: 14.4 and 23.4/sq. m., and 16.6 and 23.6/sq. m. with the second and third experiment. The dynamic, light intensity, and content of toxic gases along with the homogenization of air in the birds' vital zone were followed up. Differences were established which were defined by the higher density of raising, and which, acting as a constellation on the organism might lower the effectiveness of the technologies employed.

Air↗
PubMed1983

The occurrence of different levels of G gamma chain and of the A gamma T variant of fetal hemoglobin in newborn babies from several countries.

The gamma chain compositions of the fetal hemoglobins of 2453 newborn babies from East Asian countries (1350 babies), from Italy, Yugoslavia, Bulgaria, and Georgia (417 Caucasian babies), and 686 black babies from Georgia were determined by high pressure liquid chromatography. Unusual results for a limited number of babies were confirmed by chemical analyses, and were evaluated further by family studies. Statistical analyses indicated high gene frequencies for the A gamma T chain in Italian (f = 0.237), Yugoslavian and Bulgarian (f = 0.238), and white Georgia babies (f = 0.224), a lower frequency in Japan (f = 0.178), and India (f = 0.173), and particularly in mainland China (f = 0.079). The A gamma T gene frequency in normal (AA) Black babies was 0.102. When a beta S or beta C mutation was also present this frequency was greatly decreased, particularly in babies with the AC condition (f = 0.036). These results suggest the near absence of the A gamma T mutation on the chromosome also carrying the beta C determinant. Most babies had the expected G gamma values which vary between 60 and 80%, but several (mainly black) babies had higher values (between 80 and 90%), while one normal black baby had a G gamma value of (nearly) 100%. This condition may be a form of A gamma +1-thalassemia and has been discussed in detail elsewhere (Blood 58:491-500, 1981). Thirty-five clinically normal (mainly Chinese, Indian, and Japanese) babies had G gamma values of about 40%. Twenty-six babies had A gamma I values of about 60%, while the remaining nine babies had A gamma T and A gamma I chains in a ratio of either 1 to 2 or 1 to 1. Two additional newborns did not produce any G gamma chains, but had only A gamma I chains or A gamma T chains. Family studies failed to indicate a specific hematological abnormality. These unusual ratios between the G gamma and A gamma (either A gamma I or A gamma T) chains have led to speculations regarding possible genetic abnormalities present in these infants.

China↗
PubMed1983

[Effect of artificial air ionization on broilers].

Tested was the artificial ionization of the air in climatic chambers in attempts to maintain the abiotic ecologic factors within the parameters required by the industrial technology of raising. The feeding and raising of birds were carried in accordance with the provisions of the Bulgarian State Standard requirements. The experiments were carried out with day-old chick broilers divided into two equated groups. All parameters of the production milieu in which the groups were kept were unified with the exception of the ionization of air. The latter was effected following the pattern of a special programme worked out by the authors' team, providing for various exposures and concentrations of the ions in dependence on the age of birds. The investigation of the abiotic and biotic factors acting in the two chambers has revealed a reliable drop of the microbial contamination of the air under the effect of artificial ionization. It has been found that air ionization applied according to the tested programme stimulates the life processes in the body of broilers as evidenced by the anabolic processes with proteins, the higher vitamin A and E level in the liver, and the activation of haemopoiesis. As the result of the reduced microbial contamination of the air and the biologic action of the air ions on the body of the birds in the test group higher weight was obtained (by 19 g) as against the controls at a lower feed intake per unit of gain, with higher indices of the poultry meat. The chemical investigation of such meat of the test group birds has revealed higher protein and essential amino acid content.

Air Ionization↗
PubMed1981

The use of globin chain electrophoresis in polyacrylamide gels for the quantitation of the G gamma to A gamma ratio in fetal hemoglobin.

Polyacrylamide gel electrophoresis (PAGE) in the presence of urea, acid, and Triton X-100 was used for determination of the G gamma to A gamma ratio in human Hb F. The data compared most favourable with results obtained by a HPLC procedure and by a chemical procedure. Moreover, its accuracy and reproducibility was determined. The presence of Hb A2 in a sample with Hb F level below 10% interferes with the determination because of the nearly identical electrophoretic mobilities of the delta and G gamma chains. Thus, the removal of Hb A2 is required. Samples free fo Hb A2 but with a Hb F level as low as 2% can be analyzed with an accuracy of about 5%. The PAGE method has been applied to the Hb F of 63 subjects with beta thalassemia and related conditions, and the results of these analyses are included in this communication.

Chemical Phenomena↗
PubMed1981

[Changes in the biochemical and hematological indices of chickens raised under high temperature and humidity].

Biochemical and hematological investigations were carried out with broilers raised at extreme temperature and humidity regimes-high temperature in combination with high relative humidity. Under the effect of high temperature (30-35 degrees C) and high relative humidity of the air (85-95 per cent) there was noted a rise of the lymphocytes and monocytes and a drop of the basophile, eosinophile, and pseudoeosinophile leukocytes in the white blood picture. After vaccination of the birds of the test groups with the vaccinal La Sota strain the blood serum showed negative titers. It was found that the Ca and P content in the blood serum of such broilers was higher as compared with that of the control group.

Animals↗
PubMed1981

[Scientific and applied aspects of veterinary ecological control over the industrial technologies in animal husbandry].

In connection with the transformation of animal breeding and putting it on an industrial base ecologization becomes a strategic trend in this branch of national economy too. Ecologization of industrial stock breeding is associated with the solution of two basic groups of problems: --autoecologic. Measures to optimize the abiotic and biotic ecologic factors in view of the maximum and paying substantiation of the genetic potential of productivity of breeds on the industrial complexes. --biocenologic. Developments that lead to the limitation of contamination of the biosphere with waste products, reducing the lines of the technologic processes on the animal breeding complexes. The characteristic features on the animal breeding complexes are referred to as an artificial ecosystem: limited number of populations and reduced componency, leading role of the antropogenic factors, incomplete turnover and intensive use of substance and energy 'taken' from other natural ecosystems, and necessity of energy input. On such base an evaluation is made of the technologic designs and the need is stated to optimize all ecologic factors. Good results are stated with the optimization of the electric properties of the air. A reassessment is made of the existing technologic designs concerning the disposal of manure. Motivation is the necessity of producing biogas from FYM obtained in raising animals and birds without litter.

Animal Husbandry↗
PubMed1980

[Effect of population density on the raising of broiler chickens].

Experiments were carried out to study the influence of density in industrial broiler-raising. They took place during different seasons of the year and with a different density of habitation (12, 14, 16, 18, 20 and 22 pieces on m2) and through an optimization of technological indices in broiler-raising. The dynamism of microclimatic indices was traced out (temperature, humidity, gas composition, dust and microbe contamination of air in the buildings having a different density of habitation. Hematological and biochemical studies were carried out concerning total protein, protein fractions, contents of hemoglobin and number of erythrocytes, as well as the contents of alkaline reserves of blood. The experiments were also devoted to the growth and development, the consumption of fodder for a single unit of production, the morbidity rate and the death rate with chickens raised in different density. It was proved that the density of habitation exerts an influence over microclimatic indices. If the density is greater the contents of ammonia in the buildings is by 1.5 times over the zoohygienic requirements. Under the influence of the density of habitation certain changes occurred concerning the hematological and biochemical indices of blood. A correlation was observed between the density of habitation and the development of some diseases. Certain changes occurred also in the growth and in the development of broilers. By virtue of the results obtained, suggestions are put forward to optimize the density of habitation in industrial broiler-raising.

Animal Husbandry↗